Why Choose the Right Category?
• Cat 0–1: Efficient for typical, low-risk jobs; faster and lower cost.
• Cat 2: Suited for designs with moderate complexity—adds rigor with independent calculations.
Cat 3: Mandatory for high-risk or innovative scaffold systems, ensuring full impartiality and compliance with BS 5975 and client/contractor requirements.
Scaffold CAT 3 CHECK
BS 5975 defines four levels of design review—Cat 0 through Cat 3—based on complexity, originality, and risk. The higher the category, the greater the independence of the checker from the original design.
Category 0 (Cat 0)
• Scope: Applies only to standard solutions, like basic system scaffolds conforming to TG20 or proprietary tables.
• Check focus: Confirm that site conditions align with the manufacturer's use limitations.
• Checker: Another member of the same site or design team.
Category 1 (Cat 1)
• Scope: Simple bespoke designs — e.g., light formwork, needling, simple props or falsework resisting gravity only.
• Check method: Based on standard methods and literature; calculations are reviewed but not independently redone.
• Checker: A different member of the same design team.
Category 2 (Cat 2)
• Scope: More complex designs involving soil interpretation, excavation support, foundation works, steel connections, top restraints, etc.
• Check method: Checker receives brief, drawings, and methodology—but not original calculations—and must perform independent calculations, producing a full separate analysis.
• Checker: A different engineer or office—not involved in the original design and offering independence.
Category 3 (Cat 3)
• Scope: The most complex or innovative projects—such as façade retention, tunnels, basement excavations, Network Rail, and other bespoke or novel systems requiring extensive engineering judgment.
• Check method: Checker independently reviews all aspects—brief, drawings, methodology—and carries out fully separate calculations and design.
• Checker: Must be a completely separate organisation, providing the highest level of impartiality.
• Undertake independent calculations, reviews, and reporting.
• Provide full impartial design verification by a separate organisation.
• Deliver a Cat 3 certificate confirming compliance with BS 5975, TG20, NASC, Network Rail, TFL, etc.
Need help determining which category applies to your project, or want to start a Cat 3 review?
We are happy to help!
How Our Service Fits
+44 07896979966 info@alpha-scaffolddesign.ukA scaffold design Cat 3 Check is the highest level of independent review for scaffold designs under BS 5975. It applies when the design is complex, innovative, high-hazard, or novel—such as for façade retention, suspended scaffolds, Network Rail or nuclear projects. Unlike Cat 2, it must be carried out by a completely separate organisation from the initial designer.
